172 research outputs found
Renormalization of chiral nuclear forces with multiple subtractions in peripheral channels
We analyse the renormalization of the of two-nucleon interaction with
multiple subtractions in peripheral waves considering two chiral forces at
N3LO. Phase shifts at low energies are then computed with several subtraction
points below \mu = 10 / fm. We show that for most peripheral waves the phase
shifts have nearly no dependence on the renormalization scale. In two cases the
phase shifts converge slowly as the renormalization scale approaches \mu = 1 /
fm and in one case the phase shifts presented oscillations with respect to the
subtraction point \mu.Comment: 21 pages, 12 figures, to appear in the special issue "Few-Body
Systems in High Energy Physics" (AHEP
Phase transition of the nucleon-antinucleon plasma at different ratios
We investigate phase transitions for the Walecka model at very high
temperatures. As is well known, depending on the parametrization of this model
and for the particular case of a zero chemical potential (), a first
order phase transition is possible \cite{theis}. We investigate this model for
the case in which . It turns out that, in this situation, phases
with different values of antinucleon-nucleon ratios and net baryon densities
may coexist. We present the temperature versus antinucleon-nucleon ratio as
well as the temperature versus the net baryon density for the coexistence
region. The temperature versus chemical potential phase diagram is also
presented.Comment: 5 pages, 8 figure
On the q-deformation of the NJL model
Using a q-deformed fermionic algebra we perform explicitly a deformation of
the Nambu-Jona-Lasinio (NJL) Hamiltonian. In the Bogoliubov-Valatin approach we
obtain the deformed version of the functional for the total energy, which is
minimized to obtain the corresponding gap equation. The breaking of chiral
symmetry and its restoration in the limit are then discussed.Comment: 5 eps figure
Nucleon-nucleon scattering within a multiple subtractive renormalization approach
A methodology to renormalize the nucleon-nucleon interaction, using a
recursive multiple subtraction approach to construct the kernel of the
scattering equation, is presented. We solve the subtracted scattering equation
with the next-leading-order (NLO) and next-to-next-leading-order (NNLO)
interactions. The results are presented for all partial waves up to ,
fitted to low-energy experimental data. In our renormalizaton group invariant
method, when introducing the NLO and NNLO interactions, the subtraction energy
emerges as a renormalization scale and the momentum associated with it comes to
be about the QCD scale (), irrespectively to the partial wave.Comment: Final versio
Block-diagonal similarity renormalization group and effective nucleon-nucleon interactions
We apply the block-diagonal similarity renormalization group to a simple toy-model for the nucleon-nucleon (N N) interaction in the S-1(0) channel, aiming to analyze the complementarity between the explicit and the implicit renormalization approaches in nuclear physics. By explicit renormalization we mean the methods based on the wilsonian renormalization group in which high-energy modes above a given cutoff scale are integrated out while their effects are replaced by scale dependent effective interactions consistently generated in the process. We call implicit renormalization the usual procedure of cutoff effective theories in which the high-energy modes above the cutoff scale are simply removed and their effects are included through parametrized cutoff dependent counterterms whose strengths are fixed by fitting low-energy data. We compare the effective interactions obtained in both schemes and find a wide range of cutoff scales where they overlap. We further analyze the role played by the one-pion exchange (OPE) considering a delta-shell plus OPE representation for the N N interaction.We apply the block-diagonal similarity renormalization group to a simple toy-model for the nucleon-nucleon (NN) interaction in the 1 S 0 channel, aiming to analyze the complementarity between the explicit and the implicit renormalization approaches in nuc706FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informação13th International Workshop on Hadron PhysicsE.R.A. would like to thank the Spanish DGI (Grant FIS2011-24149) and Junta de Andalucia (Grant FQM225). S.S. is partially supported by FAPESP and V.S.T. thanks FAEPEX, FAPESP and CNPq for financial support
Running of the contact interactions in chiral N3LO potentials from subtractive renormalization
In this work a subtracted kernel renormalization procedure (SKM) is applied to the chiral NN potential up to next-to-next-to-next-to-leading-order ((NLO)-L-3) to obtain the running of the renormalized contact strengths with the subtraction scale mu and the phase shifts for all uncoupled waves with contact interaction (S, P, D). We use two potentials constructed within the framework of Weinberg's approach to ChEFT, which provide a very accurate description of NN scattering data below laboratory energies E similar to 350 MeV, namely Epelbaum, Glockle and Meissner (N3LO-EGM) and Entem and Machleidt (N3LO-EM). For both potentials, we consider a large cutoff (30 fm(-1)) and analyze the phases and the running of the contact strengths with the subtraction point mu by making a fit of the K-matrix with five subtractions to the K-matrix from the Nijmegen II potential at low energies (E <= 20 MeV).In this work a subtracted kernel renormalization procedure (SKM) is applied to the chiral NN potential up to next-to-next-to-next-to-leading-order (N 3 LO) to obtain the running of the renormalized contact strengths with the subtraction scale μ and the ph630FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informação37th Brazilian Meeting on Nuclear PhysicsS.S. is partially supported by FAPESP and V.S.T. would like to thank FAEPEX, FAPESP and CNPq for financial support
Subtractive Renormalization Of The Njl Model
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)In this work, we apply a subtractive renormalization method to the SU(2) Nambu-Jona-Lasinio (NJL) model in Born approximation and compare the results obtained here with those achieved by the standard momentum cutoff regularization. We have computed the dynamical quark mass, the chiral condensate, the pion mass and the quark-antiquark T-matrix as a function of the cutoff Λ and the subtraction scale ξ. We have shown that both approaches give similar results and the dependence of the physical quantities on the subtraction point ξ is much weaker than the dependence on the cutoff Λ. © Published under licence by IOP Publishing Ltd.706Section 5CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP, São Paulo Research FoundationConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)13th International Workshop on Hadron Physics22 March 2015 through 27 March 201512266
Nonlinear Klein-Gordon equation and the Bose-Einstein condensation
El interés por la ecuación de Klein-Gordon con diferentes potenciales ha aumentado en los últimos años debido a su posible aplicaciones en Cosmología, Física de Hadrones y Física de Altas Energías. En este trabajo, investigamos las soluciones de la ecuación de Klein–Ecuación para bosones bajo la influencia de un potencial externo utilizando el método de Feshbach-Villars. Presentamos resultados detallados en dos casos: el potencial de Coulomb y el potencial armónico. Para el segundo caso, estudiamos los efectos de la auto-interacción de partículas dentro de una aproximación de de campo medio. Mostramos que nuestros resultados convergen suavemente a la solución de la ecuación de Schrödinger para los mismos sistemas a medida que disminuyen los efectos relativistas.
En inglés: The interest in the Klein–Gordon equation with different potentials has increased in recent years due to its possible applications in Cosmology, Hadron Physics and High-Energy Physics. In this work, we investigate the solutions of the Klein–Gordon equation for bosons under the influence of an external potential by using the Feshbach–Villars method. We present detailed results for two cases: the Coulombic potential and the harmonic potential. For the latter case, we studied the effects of self-interacting particles by adopting a mean-field approach. We show that our results converge smoothly to the solution of the Schrödinger equation for the same systems as the relativistic effects diminish.FQM-225CNPq-Brazil 304244/2018-0Consejería de ConocimientoConselho Nacional de Desenvolvimento Científico e TecnológicoFAEPEX 2019/010889-1, 3258/19Investigación y Universidad of the Junta de AndalucíaJunta de Andalucía-Consejería de Economía y Conocimiento 2014-2020 Operational ProgramFundação de Amparo à Pesquisa do Estado de São Paulo
2021/12954-5Conselho Nacional de Desenvolvimento Científico e Tecnológico
306615/2018-5European Regional Development Fund
RYC-2016-20678, SOMM17/6105/UGRJunta de Andalucía
A-FQM-178-UGR18, FQM-225Instituto Nacional de Ciência e Tecnologia: Física Nuclear e Aplicações
2016/17612-7, 464 898/2014-5Consejería de Conocimiento, Investigación y Universidad, Junta de Andalucí
Impact of a magnetic field on the thermodynamics of magnetized quark matter
We investigate the effect of a magnetic field on the thermodynamics of magnetized quark matter at finite temperature. By using the Nambu Jona-Lasino (NJL) model, we show that the lattice results for the quark consensate can be reproduced when the coupling constant G of the model decreases with the magnetic field and the temperature. Our results show that thermodynamic quantities and quark condensates are very sensitive to the dependence of G with the temperature, even in the absence of a magnetic field.We investigate the effect of a magnetic field on the thermodynamics of magnetized quark matter at finite temperature. By using the Nambu Jona-Lasino (NJL) model, we show that the lattice results for the quark consensate can be reproduced when the coupling706FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESC - FUNDAÇÃO DE AMPARO À PESQUISA E INOVAÇÃO DO ESTADO DE SANTA CATARINACNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informaçãosem informação13th International Workshop on Hadron PhysicsWe thank G. Endrodi for helpful discussions and for providing the lattice data for u and d quark condensates. We also thank FAEPEX, FAPESP, FAPESC and CNPq for financial support
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